issue when copying previous result

[primer]

Hello,
I've got a weird issue.
you know you can touch one of previous result from the "stack", then calculator let you copy it for edition. (works also on virtual calculator, by clicking).
Usually it works nice... but I found a case when a simple mathematical expression is modified on copy !

see printscreen : look how sqrt(6) becomes 6. (this is in CAS mode)

note : it's in french, the 5th key "copy" is wrote "copier" in my screen.
note 2 : I call it the "stack" I do know it's not really a stack like in RPN, but I don't know how to call it.

Thank you,
Best Regards.